Flying solo is in–in a serious way. A New York TimesQ&A with Eric Kilnenberg, NYU sociology professor and author of the new book “Going Solo,” leads with the facts:

In 1950, 22 percent of American adults were single. Now that number is almost 50 percent. One in seven adults lives alone. Half of all Manhattan residences are one-person dwellings.

Kilnenberg has done his research. He spent a decade studying the phenomenon while working on his book, and he has all kinds of good explanations for those numbers. There’s less stigma than there once was around being single. People crave privacy and personal space–tough to preserve when you’re sharing a bathroom. From another piece he wrote several weeks ago,

Living alone comports with modern values. It promotes freedom, personal control and self-realization–all prized aspects of contemporary life.

And Kilnenberg’s not the only one digging in. Melanie Kurtin enumerated what keeps her from committing here and Dominique Browning did the same thing here, while Kate Bolick’s much-discussed piece in The Atlantic, “All the Single Ladies,” leads with a simple confession:

In 2001, WHEN I was 28, I broke up with my boyfriend. Allan and I had been together for three years, and there was no good reason to end things. He was (and remains) an exceptional person, intelligent, good-looking, loyal, kind. My friends, many of whom were married or in marriage-track relationships, were bewildered. I was bewildered. To account for my behavior, all I had were two intangible yet undeniable convictions: something was missing; I wasn’t ready to settle down.

And this, I think, really gets at the truth behind our reluctance to commit: to borrow–and tweak–a phrase from a long-ago presidential campaign, It’s too many choices, stupid!

When we’re told that we can have it all, that everything is on the table, why would we ever commit to anything? Even if we know we love the thing to which we’re committing, we can’t help but wonder about all the things we didn’t choose.

And I’m not just talking about relationships.

Too many options applies to commitment of the romantic sort, sure, but also to jobs and where we should live and what kind of life we should have. Passion or paycheck? Security or freedom? Long hair or short? High heels or hiking boots?

Deciding, by definition, means “to kill.” Choosing one thing means you’re killing the possibility of having the other. And when we’re raised on the idea that anything’s possible–and every option is available–we see choosing anything as settling. And, of course, it is–it’s settling for something less than everything.

When you decide to take one path, there’s a risk of missing out on something–something we often imagine to be glorious, the proverbial greener grass–waiting for us at the end of another. As Hannah, a woman we profile in Undecided, put it:

The grass is always greener. Like, do I want to move to San Francisco? Colorado? South America? Will life be any better in any of those places? Probably not. But it might be, so there’s that risk that I’m taking by not moving.

This mindset is so prevalent, some worry we have an entire generation of commitmentphobes on our hands. Psychologist Jeffrey Jensen Arnett is trying to get the in-between stage–the years when we try different jobs/relationships/cities/hairstyles on for size–designated as a distinct life stage, one he calls Emerging Adulthood. People don’t spent their entire career with one company anymore–the very idea sounds Flinstonian. Nor do they generally marry their high school sweethearts. To paraphrase Hannah, There’s that risk we’re taking by not checking out what else is out there. We have the whole world to explore first!

For women in particular, it’s excruciating. Because, in addition to that message–that we can do anything!–we were fed another, often from the women just a generation or two older than us, who weren’t afforded the same opportunity: that we’re so lucky that we can do anything. And combined, they leave many of us shouldering a load of responsibility.

This bounty of opportunity is so new that we were sent off to conquer it with no tools–just an admonishment that we’d best make the most of it.

We know we’re blessed to have all of these options. We get it. And so is it any wonder we want a shot at each and every one of them?

But therein lies the rub.

We want to travel, but can’t take off whenever we feel like it if we’re also going to get our business off the ground–and featured in Oprah. We want a family, but that’d mean that packing up and moving to Cairo or New Orleans on a whim is pretty much off the table. We want to be there for our daughter’s every milestone, yet we also want to model what a successful career woman looks like. We want torrid affairs and hot sex, but where would that leave our husbands? We want financial security and a latte on our way to the office every morning, but sit in our ergonomically correct chairs daydreaming about trekking through Cambodia with nothing but our camera and mosquito net. We want to be an artist, but have gotten rather used to that roof over our heads. We want to be ourselves, fully and completely, but would like to fit in at cocktail parties, too. (And when on earth are we going to find the time to write our novel??)

We want to do it all, to try it all before we buy! And that, I believe, is what’s at the root of the cold feet. Choices are hard. Damn hard. And every one of them entails a trade-off. The work is in accepting that–and in finding out who you are right down at your core, and figuring which of those trade-offs you can live with.